The drawing of Steelcord steel wires through dies is carried out under extremely severe temperature and pressure conditions due to significant friction that then develops between the wire and the dies. This results in rapid wearing of the die surface and of that of the wire, risks of breaking and appearance of surface defects on the wire. A too rapid increase in the diameter of the die and therefore of the drawn wire is unacceptable from an industrial viewpoint.
To overcome the above problems, or at least minimize them, it is known to use oily or aqueous type lubricants.
Under the most extreme conditions, aqueous lubricants are generally preferred due to their superior metal-cooling capacity. Other advantages they have are being easy to use, not very polluting and more economical.
The most commonly used commercial drawing lubricants are aqueous emulsions (see, for example, document FR 1 037 447) composed of different fatty constituents in liquid form put into emulsion in the aqueous phase via a combination of surfactants. Various additives may be dissolved in the aqueous or fatty phase.
Lubricants in the form of an aqueous dispersion, based on a solid fatty phase (or “wax”) dispersed in the aqueous phase, generally stabilized by a combination of surfactants, may also be used. Aqueous dispersions comprising, in particular, solid particles of waxes based on bisamides such as ethylene bis(stearamide) (abbreviated hereinbelow to “EBS”) are also widespread; they are known for the cold working of metals, in particular for rolling (see, for example, documents WO 02/062931 or US 2004/072702, U.S. Pat. No. 4,481,038).
Obtaining more efficient lubrication is a constant concern in the field of drawing Steelcord steel wires, in order to achieve, in particular, at least one of the following industrial objectives:                higher productivity, for example a faster drawing rate;        a lower die replacement frequency;        less breakage of wires when they are being drawn; and        the possibility of drawing harder steels, having a higher carbon content, under production conditions similar to those used for the drawing of less hard steels.        